Eight soybean cultivars (Doko, Bossier, Savana, Paraná and Cristalina) were crossed in a diallel design. Plants of the F 1 generation and their parents were evaluated under short-day conditions for the determination of the general (GCA) and specific (SCA) combining ability. The estimated GCA and SCA values were significant for the evaluated traits except for the "total cycle". Highest GCA effects for the traits "days to flowering", "plant height", "insertion height", "number of branches" and "total cycle" were estimated for the cultivars Doko, Cristalina and Savana. The variability observed in the trait "days to flowering" can, for the most part, be explained by additive effects.

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-Stem canker caused by the fungus Diaporthe phaseolorum f. sp. meridionalis is a disease that limits soybean cultivation. Phenotypic evaluations aiming at disease resistance require labor-intensive processes, as for instance handling and transport of phytopathogens. The use of DNA markers in the selective procedures eases certain phases, besides being practical, safe and reliable. A RAPD fragment of 588pb was identified among bulks of resistant and susceptible plants in the cross BR92-15454 (R) x IAC-11 (S). Through co-segregation, the distance between the resistance locus and the fragment was estimated at 7.4 ± 2.1 cM, with a Lod max. of 23.072 (first year) and at 6.0 ± 3.4 cM with a Lod max. of 7.806 (second year). The fragment was converted into a SCAR marker and digested with enzyme

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